The portable radiotelephone, also known as a "cellular" telephone, has become an increasingly popular item for both personal and commercial use. Some users, such as doctors, salespersons, real estate brokers, and the like, often find that carrying a telephone on their person or in a motor vehicle is quite helpful and convenient, and in some instances almost essential, to perform their professional tasks.
To further increase the convenience afforded by radiotelephones, the trend has been for radiotelephone units to be increasingly smaller for easier storage and portability. To this end, the "flip" phone was developed. A flip phone, an example of which is shown in Design U.S. Pat. No. 304,189 to Nagele et al., comprises a handset portion and a "flip" portion. The handset portion houses push buttons for activating the radiotelephone and sending dialing tones, a signal receiving unit and amplifier, and other components associated with the operation of the radiotelephone. The flip portion, which may house the mouthpiece and associated microphone, is hingedly attached to one end of the handset portion. The flip portion overlies and contacts a portion of the handset portion when the phone is inoperative. To operate the phone, the flip portion is pivoted to an open position in which it forms an angle of approximately 135 degrees with the handset portion. In this position, the phone is configured so that when the speaker is placed adjacent a user's ear, the mouthpiece microphone is positioned adjacent a user's mouth; as a result, the flip phone can be used in much the same manner as a conventional radiotelephone. The popularity of the flip phone is in large part due to the ability of the phone to fold very compactly into the closed position when not in use.
The radiotelephone typically includes structures that lock the flip cover into the both the closed and the open positions. It is particularly important that the flip cover lock snugly into the closed position; otherwise, agitation or other movement of telephone, particularly to a position in which the cover faces downwardly, may cause the phone to be activated inadvertently. It is also important that the cover lock snugly in the operative position for the user's convenience.
Because the phone relies on pivotal movement of the flip portion for its operation, the configuration and, in turn, the operation of the hinge interconnecting the flip portion with the handset can greatly influence the performance and attractiveness of the phone. The hinge may be subjected to significant levels of stress, and in particular to fatigue-based stress, due to repeated cycling of the flip portion between the operative and closed positions. If the hinge becomes fatigued after repeated pivoting cycles, it may loosen to such a degree that it does not remain in a desired position; alternatively, the hinge may fracture. Both loosening and fracture can lead to inconsistent operation of the phone.
In addition, it is desirable that, when the cover is in the closed position, it be biased toward the closed position. If biasing means are present, any slight movement of the phone that could otherwise jostle the cover out of the closed position (and thus activate the phone) will not do so. Typically biasing is provided by some type of wire spring connected with the hinge, see U.S. Pat. No. 4,897,873 to Beutler; U.S. Pat. No. 5,259,019 to Stilley. However, the inclusion of an additional component, such as a wire spring, can add both material and labor costs to the phone.
Further, it is desirable that the phone be capable of taking a conformation in which it can be placed on an underlying surface while in operation to enable the user the freedom to do so. Typically in this conformation the flip cover pivots to a position approximately 180 degrees from its closed position. In this position the operating phone can be placed upside-down on an underlying surface to free the user's hands without disconnecting the phone. See Design U.S. Pat. No. 282,738 to Nichols for an exemplary phone capable of such a configuration. Thus the hinge configuration of a radiotelephone should be include the capability of pivoting the cover to a fully open position without the operation of the hinge in the closed and operative positions being adversely affected.